Xanthan gum and similar heteropolysaccharides are currently manufactured by means of fermenting a suitable nutrient medium with a Xanthomonas organism, typically Xanthomonas campestris B-1459. The process employed involves the use of a batch method in which the inoculum medium is allowed to ferment for a period of 36-72 hours under aerobic conditions. The xanthan gum thus produced is isolated from the other components of the medium by precipitation with acetone or a low molecular weight alcohol such as methanol, in a known manner. However, because of the time required to ferment each batch, the low xanthan content of the fermented medium, and the processing required for the recovery and purification of the product, xanthan produced by batch fermentation is relatively expensive.
Insofar as I am aware, all of the installed plant capacity presently in use for the manufacture of xanthan by fermentation methods is restricted to use of the batch fermentation process. In using this particular technique, one of the chief disadvantages is the lag time required to prepare adequate quantities of inoculum (seed) for each batch run. For the quantities of nutrient medium involved in industrial operations, as much as four days time is needed to provide enough inoculum. After the fermentation has been completed and the product xanthan separated, the spent mash in the fermenter must be withdrawn and the fermenter cleaned out and sterilized before a new charge of sterile medium can be introduced.
Xanthan gum has potential application as a film forming agent, as thickeners for bodybuilding agents in edible products, cosmetic preparations, pharmaceuticals, vehicles, oilfield drilling fluids, fracturing liquids, and similar compositions and as emulsifying stabilizing and sizing agents. Xanthan also has a potential large volume use as a mobility control agent in micellar-polymer flooding. This gum possesses excellent viscosifying properties at low concentration and resistance to shear degradation and exhibits only minimal losses in viscosity as a function of temperature, pH, and ionic strength. For these reasons, xanthan is an attractive alternative to synthetic polyacrylamides for enhanced oil recovery operations.